As his week-long court testimony came to an end on Tuesday, Oscar Pistorius maintained he was innocent and had acted involuntarily when he fired the shots that killed Reeva Steenkamp. Prosecutor Gerrie Nel said Pistorius was lying and had killed his girlfriend in cold blood, but failed to win a concession from him that he had intended to fire his 9mm pistol.

"She was locked into the bathroom and you armed yourself with the sole purpose of shooting and killing her.
That is what you did," Nel stated in the high court in Pretoria. Concluding his dogged cross-examination of Pistorius, Nel asked the Paralympian athlete who, to his mind, should bear responsibility for the fact that he shot dead Reeva Steenkamp.

Pistorius responded: "I don't know, My Lady, I was scared ... I believed that there was a threat on my life." Nel demanded to know who, then, should take the blame.

Pistorius repeated that he did not know, prompting the prosecutor to ask: "Once again we should not blame you for the fact that you shot her ... Should we blame Reeva? She never told you she was going to the toilet ... should we blame her? Should we blame the government? Who should we blame for the black talon rounds that ripped through her body?"

Nel said he would argue that the court should find that Pistorius's account of the shooting on Valentine's Day last year was "so improbable that it could not reasonably, possibly be true".

Pistorius risks a life sentence for murder, but has testified that though he was ready to confront a suspected intruder hiding behind the locked door of the toilet cubicle in his home, he was not thinking when he fired the shots that hit Steenkamp in the hip, arm and head.

Changed his defence
Nel has remarked that this means the sprinter has changed his defence "from putative self-defence to involuntary action".

Pistorius's counsel Barry Roux SC returned to the issue of intention when he rose to re-examine his client briefly and asked whether he consciously pulled the trigger. Again Pistorius insisted: "As soon as I heard the noise, before I could think, I pulled the trigger ... I was overcome with a sense of terror and vulnerability."

He had told Nel that his panic was sparked by the sound of a wooden object moving. He believed that this was the door opening but later realised it could only have been the magazine rack inside the toilet cubicle moving.

But Nel contends that Pistorius not only fired deliberately but shifted his aim to make sure that he hit Steenkamp after she fell backwards onto the magazine rack, betraying her position behind the door. Pistorius denied that Steenkamp fell onto the rack, suggesting that the police had moved it after the fact – a recurring theme in his testimony.

But Nel said it was another instance of Pistorius tailoring his testimony. "That magazine rack never moved. That was where she ended up, with her head on the toilet," Nel told Pistorius during cross-examination. "This is getting more and more improbable and you are tailoring more and more."

He asked Pistorius on Tuesday why he moved through his house screaming while looking for Steenkamp after the shooting, but stopped once he had broken down the toilet door and was holding her broken body. "Now it's the opportunity to scream, Reeva, Reeva, are you fine? Why did you not scream then?" But Pistorius replied: "I don't know, what would the purpose of screaming be?"

Nel said it was in fact Steenkamp who had screamed so loudly before the shooting that neighbours were alarmed. "They heard Reeva's blood-curdling screams, they heard that when she escaped from you."

Pistorius denied this. He largely retained his composure on the witness stand on Tuesday, after Nel repeatedly accused him of staging displays of distress and remorse whenever he struggled to answer questions.

Gift card
To questioning from Roux, he revealed that Steenkamp had given him a Valentine's gift with a card in which she declared for the first time that she loved him. Pistorius has told the court that he only opened the gift months after the shooting, on August 8 last year, to mark Steenkamp's 30th birthday. However, the blonde model was born on August 19.

After he left the stand, Roux called Roger Dixon, a former senior police forensic expert, who told the court he had conducted sound and vision tests that contradicted testimony from Pistorius's neighbours. They told the court they heard a woman's screams, followed by a volley of gunshots, and saw a shadow moving in his lit bathroom window.

Dixon testified that Steenkamp was possibly reaching for the toilet door handle when she was shot – judging by splinters from the door embedded in her skin – but agreed with the state's case that she fell onto the magazine rack: "The marks are consistent with falling onto the magazine rack."

But he agreed with Pistorius's defence that police investigators had possibly compromised evidence, telling the court it was clear that one had stepped on the door and terming it "most unprofessional".

The state has asked for the trial to be adjourned to May 5 and Judge Thokozile Masipa is due to rule on that on Wednesday. – Sapa